Optical properties of "diamondlike" carbon films: An ellipsometric study

The index of refraction and extinction coefficient are measured as a function of wavelength from 254 to 633 nm using reflection-null ellipsometry. It is shown that both rf glow-discharge-deposited and ion-beam-sputtered films have the same values of $n$ and $k$ over the measured wavelength range. Calculated values of absorption coefficient indicate that the absorption edge is not reached even at near ultraviolet wavelengths. Thermal cycling up to 500°C does not change the optical properties significantly.